Biomedical subjects

Raghavendra G Mirmira

Publications and source records attributed to Raghavendra G Mirmira.

3 recordsLinked to original sources

PubMed2025

The Heterogeneity of Type 1 Diabetes: Implications for Pathogenesis, Prevention, and Treatment-2024 Diabetes, Diabetes Care, and Diabetologia Expert Forum.

This article summarizes the current understanding of the heterogeneity of type 1 diabetes from a June 2024 international Expert Forum organized by the editors of Diabetes, Diabetes Care, and Diabetologia. The Forum reviewed key factors contributing to the development and progression of type 1 diabetes and outlined specific, high-priority research questions. Knowledge gaps were identified, and, notably, opportunities to harness disease heterogeneity to develop personalized therapies were outlined. Herein, we summarize our discussions and review the heterogeneity of genetic risk and immunologic and metabolic phenotypes that influence and characterize type 1 diabetes progression (presented as a palette of risk factors). We discuss how these age-related factors determine disease aggressiveness (along gradients) and describe how variable immunogenetic pathways aggregate (into networks) to affect β-cell and other pancreatic pathologies to cause clinical disease at different ages and with variable severity (described as disease-related thresholds). Heterogeneity of pathogenesis and clinical severity opens avenues to prevention and intervention, including the potential of disease-modifying immunotherapy and islet cell replacement. We conclude with a call for 1) continued research to identify more factors contributing to the disease, both overall and in specific subgroups; 2) investigations focusing on both individuals who surpass metabolic and immune thresholds and develop diabetes and those who remain disease free with the same level of immunogenetic risk; and 3) efforts to identify where the current type 1 diabetes staging system may fall short and determine how it can be improved to capture and leverage heterogeneity in prevention and intervention strategies.

Humans↗

PubMed2025

A consensus guide to preclinical indirect calorimetry experiments.

Understanding the complex factors influencing mammalian metabolism and body weight homeostasis is a long-standing challenge requiring knowledge of energy intake, absorption and expenditure. Using measurements of respiratory gas exchange, indirect calorimetry can provide non-invasive estimates of whole-body energy expenditure. However, inconsistent measurement units and flawed data normalization methods have slowed progress in this field. This guide aims to establish consensus standards to unify indirect calorimetry experiments and their analysis for more consistent, meaningful and reproducible results. By establishing community-driven standards, we hope to facilitate data comparison across research datasets. This advance will allow the creation of an in-depth, machine-readable data repository built on shared standards. This overdue initiative stands to markedly improve the accuracy and depth of efforts to interrogate mammalian metabolism. Data sharing according to established best practices will also accelerate the translation of basic findings into clinical applications for metabolic diseases afflicting global populations.

Calorimetry, Indirect↗

PubMed2002

Quantitative assessment of gene targeting in vitro and in vivo by the pancreatic transcription factor, Pdx1. Importance of chromatin structure in directing promoter binding.

The transcription factor Pdx1 is expressed in the pancreatic beta-cell, where it is believed to regulate several beta-cell-specific genes. Whereas binding by Pdx1 to elements of beta-cell genes has been demonstrated in vitro, almost none of these genes has been demonstrated to be a direct binding target for Pdx1 within cells (where complex chromatin structure exists). To determine which beta-cell promoters are bound by Pdx1 in vivo, we performed chromatin immunoprecipitation assays using Pdx1 antiserum and chromatin from beta-TC3 cells and Pdx1-transfected NIH3T3 cells and subsequently quantitated co-immunoprecipitated promoters using real-time PCR. We compared these in vivo findings to parallel immunoprecipitations in which Pdx1 was allowed to bind to promoter fragments in in vitro reactions. Our results show that in all cells Pdx1 binds strongly to the insulin, islet amyloid polypeptide, glucagon, Pdx1, and Pax4 promoters, whereas it does not bind to either the glucose transporter type 2 or albumin promoters. In addition, no binding by Pdx1 to the glucokinase promoter was observed in beta-cells. In contrast, in in vitro immunoprecipitations, Pdx1 bound all promoters to an extent approximately proportional to the number of Pdx1 binding sites. Our findings suggest a critical role for chromatin structure in directing the promoter binding selectivity of Pdx1 in beta-cells and non-beta-cells.

Animals↗